MiR-200a is involved in rat epididymal development by targeting β-catenin mRNA.

The expression of 350 microRNAs (miRNAs) in epididymis of rat from postnatal development to adult (from postnatal days 7-70) was profiled with home-made miRNA microarray. Among them, 48 miRNAs changed significantly, in which the expression of miR-200a increased obviously with time, in a good agreement with that obtained from northern blot analysis. The real-time quantitative-polymerase chain reaction result indicated that temporal expression of rat β-catenin was exactly inversed to that of miR-200a during rat epididymal development, implying that miR-200a might also target β-catenin mRNA in rat epididymis as reported by Saydam et al. in humans. The bioinformatic analysis indicated that 3' untranslated region of rat β-catenin mRNA did contain a putative binding site for miR-200a. Meanwhile, it was found that the sequence of this binding site was different from that of human β-catenin mRNA with a deletion of two adjacent nucleotides (U and C). But the results of luciferase targeting assay in HEK 293T cells and the overexpression of miR-200a in rat NRK cells demonstrated that miR-200a did target rat β-catenin mRNA and cause the suppression of its expression. All these results show that miR-200a should be involved in rat epididymal development by targeting β-catenin mRNA of rat and suppressing its expression.